1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/pcmcia/yenta_socket.c b/drivers/pcmcia/yenta_socket.c
index 006749dc8d75..d9d005ec920c 100644
--- a/drivers/pcmcia/yenta_socket.c
+++ b/drivers/pcmcia/yenta_socket.c
@@ -1005,6 +1005,77 @@ static void yenta_config_init(struct yenta_socket *socket)
         config_writew(socket, CB_BRIDGE_CONTROL, bridge);
 }
 
+/**
+ * yenta_fixup_parent_subordinate - Fix subordinate bus# of the parent bridge
+ * @cardbus_bridge: The PCI bus which the CardBus bridge bridges to
+ *
+ * Checks if devices on the bus which the CardBus bridge bridges to would be
+ * invisible during PCI scans because of a misconfigured subordinate number
+ * of the parent brige - some BIOSes seem to be too lazy to set it right.
+ * Does the fixup carefully by checking how far it can go without conflicts.
+ * See http://bugzilla.kernel.org/show_bug.cgi?id=2944 for more information.
+ */
+static void yenta_fixup_parent_bridge(struct pci_bus *cardbus_bridge)
+{
+        struct list_head *tmp;
+        unsigned char upper_limit;
+        /*
+         * We only check and fix the parent bridge: All systems which need
+         * this fixup that have been reviewed are laptops and the only bridge
+         * which needed fixing was the parent bridge of the CardBus bridge:
+         */
+        struct pci_bus *bridge_to_fix = cardbus_bridge->parent;
+
+        /* Check bus numbers are already set up correctly: */
+        if (bridge_to_fix->subordinate >= cardbus_bridge->subordinate)
+                return; /* The subordinate number is ok, nothing to do */
+
+        if (!bridge_to_fix->parent)
+                return; /* Root bridges are ok */
+
+        /* stay within the limits of the bus range of the parent: */
+        upper_limit = bridge_to_fix->parent->subordinate;
+
+        /* check the bus ranges of all silbling bridges to prevent overlap */
+        list_for_each(tmp, &bridge_to_fix->parent->children) {
+                struct pci_bus * silbling = pci_bus_b(tmp);
+                /*
+                 * If the silbling has a higher secondary bus number
+                 * and it's secondary is equal or smaller than our
+                 * current upper limit, set the new upper limit to
+                 * the bus number below the silbling's range:
+                 */
+                if (silbling->secondary > bridge_to_fix->subordinate
+                    && silbling->secondary <= upper_limit)
+                        upper_limit = silbling->secondary - 1;
+        }
+
+        /* Show that the wanted subordinate number is not possible: */
+        if (cardbus_bridge->subordinate > upper_limit)
+                printk(KERN_WARNING "Yenta: Upper limit for fixing this "
+                        "bridge's parent bridge: #%02x\n", upper_limit);
+
+        /* If we have room to increase the bridge's subordinate number, */
+        if (bridge_to_fix->subordinate < upper_limit) {
+
+                /* use the highest number of the hidden bus, within limits */
+                unsigned char subordinate_to_assign =
+                        min(cardbus_bridge->subordinate, upper_limit);
+
+                printk(KERN_INFO "Yenta: Raising subordinate bus# of parent "
+                        "bus (#%02x) from #%02x to #%02x\n",
+                        bridge_to_fix->number,
+                        bridge_to_fix->subordinate, subordinate_to_assign);
+
+                /* Save the new subordinate in the bus struct of the bridge */
+                bridge_to_fix->subordinate = subordinate_to_assign;
+
+                /* and update the PCI config space with the new subordinate */
+                pci_write_config_byte(bridge_to_fix->self,
+                        PCI_SUBORDINATE_BUS, bridge_to_fix->subordinate);
+        }
+}
+
 /*
  * Initialize a cardbus controller. Make sure we have a usable
  * interrupt, and that we can map the cardbus area. Fill in the
@@ -1120,6 +1191,8 @@ static int __devinit yenta_probe (struct pci_dev *dev, const struct pci_device_i
         yenta_get_socket_capabilities(socket, isa_interrupts);
         printk(KERN_INFO "Socket status: %08x\n", cb_readl(socket, CB_SOCKET_STATE));
 
+        yenta_fixup_parent_bridge(dev->subordinate);
+
         /* Register it with the pcmcia layer.. */
         ret = pcmcia_register_socket(&socket->socket);
         if (ret == 0) {